Dresden 2020 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 22: Active Matter II (joint session BP/CPP/DY)
DY 22.5: Talk
Tuesday, March 17, 2020, 10:30–10:45, HÜL 386
Axisymmetric spheroidal squirmers and self-diffusiophoretic particles — Ruben Poehnl1, •Mihail Popescu2, and William Uspal1 — 1Dept. of Mech. Eng., Univ. of Hawai’i at Manoa, 2540 Dole St., Honolulu, HI 96822, USA — 2Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany
By using previously published analytical solutions for Stokes flow around a spheroid, here we investigate the motion of a spheroidal, axisymmetric squirmer in an unbounded fluid and the low Reynolds number hydrodynamic flow induced by the squirmer.
In contrast to the case of a spherical squirmer, for the spheroidal squirmer each slip mode either contributes to the velocity, or contributes to the stresslet. Additionally, and also distinct from the case of a spherical squirmer, each slip mode excites either all of the fore-aft symmetric or fore-aft asymmetric components of the flow field, respectively. Accordingly, with small modifications of the squirming pattern, a microrganism could maintain its velocity unchanged but dramatically alter the topology of the flow around it. This raises the interesting speculative question as whether the spheroidal shape is providing an evolutionary advantage, i.e., a spheroidal squirmer possesses simple means – not available to a spherical one – for acting in hydrodynamic disguise, which can be advantageous as either predator or prey.
The results are straightforwardly extended to the self-phoresis of axisymmetric, spheroidal, chemically active particles with phoretic slip.